Catalyst and process for the conversion of oxygenates to olefins

Abstract

A catalyst composition for use in the conversion of oxygenates to olefins comprises a first molecular sieve comprising a CHA framework type material and a second molecular sieve comprising an AFI framework type material, wherein said second molecular sieve is present in an amount up to 0.75% by weight of said first molecular sieve.

1 . A catalyst composition for use in the conversion of oxygenates to olefins, the catalyst composition comprising a first molecular sieve comprising a CHA framework type material and a second molecular sieve comprising an AFI framework type material, wherein said second molecular sieve is present in an amount up to 0.75% by weight of said first molecular sieve.  
   
   
       2 . The catalyst composition of  claim 1 , wherein said second molecular sieve is present in an amount up to 0.5% of by weight of said first molecular sieve.  
   
   
       3 . The catalyst composition of  claim 1 , wherein said first molecular sieve comprises a silicoaluminophosphate.  
   
   
       4 . The catalyst composition of  claim 1 , wherein said first molecular sieve comprises at least one intergrown form of a CHA framework type material and an AEI framework type material.  
   
   
       5 . The catalyst composition of  claim 1 , wherein said first molecular sieve comprises at least one intergrown form having an AEI/CHA ratio of from about 5/95 to about 40/60 as determined by DIFFaX.  
   
   
       6 . The catalyst composition of  claim 1 , wherein said first molecular sieve comprises at least one intergrown form having an AEI/CHA ratio of from about 10/90 to about 30/70 as determined by DIFFaX.  
   
   
       7 . The catalyst composition of  claim 1 , wherein said first molecular sieve comprises at least one intergrown form having an AEI/CHA ratio of from about 15/95 to about 20/80 as determined by DIFFaX.  
   
   
       8 . The catalyst composition of  claim 5 , wherein said first molecular sieve has an X-ray diffraction pattern comprising at least one reflection peak in each of the following ranges in the 5 to 25 (2θ) range:  
     
       
         
               
             
                   
               
                   
               
                 2θ (CuKα) 
               
                   
               
                 9.3-9.6 
               
                 12.7-13.0 
               
                 13.8-14.0 
               
                 15.9-16.1 
               
                 17.7-18.1 
               
                 18.9-19.1 
               
                 20.5-20.7 
               
                  23.7-24.0. 
               
                   
               
                   
               
           
              
              
              
              
             
             
              
              
              
              
              
              
              
              
              
              
             
          
         
       
     
   
   
       9 . The catalyst composition of  claim 1 , wherein said first molecular sieve comprises first and second intergrown forms each of an AEI framework type material and a CHA framework type material.  
   
   
       10 . The catalyst composition of  claim 9 , wherein said first intergrown form has an AEI/CHA ratio of from about 5/95 to about 40/60 as determined by DIFFaX analysis and said second intergrown form has a different AEI/CHA ratio from said first intergrown form.  
   
   
       11 . The catalyst composition of  claim 10 , wherein said second intergrown form has an AEI/CHA ratio of about 50/50 as determined by DIFFaX analysis.  
   
   
       12 . The catalyst composition of  claim 1 , wherein said second molecular sieve comprises an aluminophosphate, a silicoaluminophosphate or a substituted form thereof.  
   
   
       13 . The catalyst composition of  claim 11 , wherein said second molecular sieve comprises SAPO-5.  
   
   
       14 . The catalyst composition of  claim 11 , wherein said second molecular sieve comprises ALPO-5.  
   
   
       15 . The catalyst composition of  claim 1  wherein said amount of said first molecular sieve is determined according to the equation:  
       A 1 /A 2    
     wherein A 1  is the area under under any X-ray diffraction peak of said composition centered at a two-theta value of about 7.3° and A 2  is the area under any X-ray diffraction peak of said composition centered at a two-theta value of about 9.4°.  
   
   
       16 . A method of producing a catalyst for use in the conversion of oxygenates to olefins, the method comprising: 
 (a) preparing a synthesis mixture suitable for producing a first molecular sieve comprising a CHA framework material;    (b) crystallizing said synthesis mixture;    (c) recovering from said synthesis mixture a crystalline composition comprising said first molecular sieve and a second molecular sieve comprising an AFI framework type material; and    (d) preparing a catalyst from the crystalline composition recovered in (c), wherein said catalyst comprises said first molecular sieve and said second molecular sieve and wherein said second molecular sieve is present in an amount up to 0.75% by weight of said first molecular sieve.    
   
   
       17 . The method of  claim 16 , wherein said crystalline composition recovered in (c) comprises said second molecular sieve in an amount up to 0.75% by weight of said first molecular sieve.  
   
   
       18 . The method of  claim 16 , wherein said crystalline composition recovered in (c) comprises said second molecular sieve in an amount in excess of 0.75% by weight of said first molecular sieve and the preparing (d) includes mixing said crystalline composition with additional first molecular sieve to reduce the amount of said second molecular sieve in said catalyst to 0.75% by weight or less of said first molecular sieve.  
   
   
       19 . The method of  claim 16 , wherein said second molecular sieve is present in said catalyst in an amount up to 0.5% of by weight of said first molecular sieve.  
   
   
       20 . A method of producing a catalyst for use in the conversion of oxygenates to olefins, the method comprising mixing a first molecular sieve composition with a second molecular sieve composition to produce a third molecular sieve composition, wherein 
 (a) the first molecular sieve composition comprises a first molecular sieve and a second molecular sieve, said first molecular sieve comprising a CHA framework type material, and said second molecular sieve comprising an AFI framework type material, said second molecular sieve being present in an amount in excess of 0.75 wt. % of the first molecular sieve;    (b) the second molecular sieve composition comprises a molecular sieve comprising a CHA framework type material; and    (c) the ratio of the first and second molecular sieve compositions being such that the third molecular sieve composition contains up to 0.75% of the second molecular sieve by weight of molecular sieve comprising a CHA framework type material.    
   
   
       21 . The method of  claim 20 , wherein the third molecular sieve composition contains up to 0.5% of the second molecular sieve by weight of molecular sieve comprising a CHA framework type material.  
   
   
       22 . The method of  claim 20 , wherein at least one of the first and second molecular sieve compositions also comprises a matrix and/or binder.  
   
   
       23 . A process for converting an oxygenate-containing feedstock to a product comprising olefins, the process comprising contacting the feedstock under oxygenate to olefin conversion conditions with a composition comprising a first molecular sieve comprising a CHA framework type material and a second molecular sieve including a AFI framework type material, wherein said second molecular sieve is present in an amount up to 0.75 wt % of by weight of said first molecular sieve.  
   
   
       24 . The process of  claim 23 , wherein the oxygenate-containing feedstock comprises methanol, dimethyl ether, or mixtures thereof and the product comprises ethylene and propylene.  
   
   
       25 . The process of  claim 23  and further comprising converting the olefins to polymer.